Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Animal studies show stem cells might make biological pacemaker


In experiments in the lab and with guinea pigs, researchers from Johns Hopkins have found the first evidence that genetically engineered heart cells derived from human embryonic stem (ES) cells might one day be a promising biological alternative to the electronic pacemakers used by hundreds of thousands of people worldwide.

Electronic pacemakers are used in children and adults with certain heart conditions that interfere with a normal heartbeat. However, these life-saving devices can’t react the way the heart’s own pacemaker normally does -- for example, raising the heart rate to help us climb stairs or react to a scary movie.

In the researchers’ experiments, described in the Dec. 20 advance online edition of Circulation, human ES cells were genetically engineered to make a green protein, grown in the lab and then encouraged to become heart cells. The researchers then selected clusters of the cells that beat on their own accord, indicating the presence of pacemaking cells. These clusters triggered the unified beating of heart muscle cells taken from rats, and, when implanted into the hearts of guinea pigs, triggered regular beating of the heart itself.

"These implanted cells also responded appropriately to drugs used to slow or speed the heart rate, which electronic pacemakers can’t do," says study leader Ronald Li, Ph.D., assistant professor of medicine. "But many challenges remain before this technique could be used for patients. We want to bring this to the clinic as fast as possible, but we need to be extremely careful. If this process isn’t done properly, it could jeopardize a very promising field."

The genetic engineering of the ES cells, accomplished by Tian Xue, Ph.D., a postdoctoral fellow at the School of Medicine, inserted a gene (for green fluorescence protein) so that the human cells would be easily distinguished from animal cells in the experiments. Since the engineered cells survived and worked properly, other more clinically important genetic engineering of the cells also will probably not interfere with the cells’ fate, say the researchers.

"To our knowledge, these are the first genetically engineered heart cells derived from human ES cells," notes Xue. "We’re now using genetic engineering to customize the pacing rate of these cells, for example. For any future clinical applications, you want to make sure that the beating rate is what you want it to be."

First isolated at the University of Wisconsin, the human ES cells used by the researchers have the natural ability to become any type of cell found in the human body, and therefore they hold the potential to replace damaged cells. But such applications await proof that the desired type of cells can be obtained, isolated and controlled, because expected risks include primitive cells developing into tumors or implanted cells being rejected.

In the researchers’ experiments, clusters of beating human heart cells derived from ES cells were injected into the heart muscle of six guinea pigs. A few days later, the researchers destroyed each animal’s own pacemaking cells, located near the point of injection, by freezing them. Careful electrical measurements on the hearts revealed a new beat, coordinated by the implanted human cells and slower than the animals’ normal heart rate -- likely reflecting humans’ lower heart rate.

To prove that the human heart cells were controlling the beat of the guinea pigs’ hearts, colleagues Fadi Akar, Ph.D., and Gordon Tomaselli, M.D., conducted careful experiments that showed exactly where the electrical signal originated and followed the signal’s conduction across the heart’s surface. Sure enough, the signal started from the transplanted human cells, easy to locate because of their fluorescence.

"We’ve answered three very important questions," says Xue. "We’ve shown that these human cells survived when we put them into the animals, they were able to combine functionally with the animal’s heart muscle, and they didn’t create tumors for as long as we have watched."

But new questions have come up because of these promising results, notes Li. For instance, the researchers don’t know why the animal’s immune system didn’t attack and kill the human cellular "invaders " -- that was a surprise. One possibility is that the cluster of cells didn’t connect enough with the animal’s circulatory system to trigger an immune response, but more experiments will be necessary to see whether that’s the case and, if so, how that might affect the implanted cells’ long-term survival.

The researchers weren’t too surprised that no tumors formed over the course of a few months of observation, however, since they had selected beating heart cells and left behind any cells that weren’t adequately specialized.

The stem cell approach isn’t the first Hopkins research to create a biological pacemaker, but it is likely to be a better choice if the heart is very damaged. In 2002, Hopkins scientists reported that inserting a particular gene into existing heart muscle cells in a guinea pig allowed the cells to create a pacemaking signal. If heart damage is extensive, however, it might be preferable to introduce new pacemaking cells, rather than to convert existing cells into pacemakers, notes Li.

Joanna Downer | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München

nachricht Second research flight into zero gravity
21.10.2016 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>